Griefing

Griefing refers to the act of a player ruining the gaming experience of another player on purpose (though this is debatable from one server to another - see below). The most obvious form of griefing is constant stalking of a player, by either following him or her for no reason, whispering useless messages, repeatedly sending them invitations after they decline, etc.

Blizzard isn't against griefing behavior when there's a PvP remedy (if you can get together a group of allies to trounce the offending party or simply kill all the mobs quickly, the problem is solved), but when the griever is impossible to attack (is not set PvP, or is of the same faction as his targets), there is no such PvP remedy.

Griefing like corpse and graveyard camping can be prevented on PvE realms simply by turning off your characters PvP flag.

A griefer in World of Warcraft is almost always one who PKs or trainsmobs to other characters, but the term includes any activity specifically designed to hamper another player's gameplay, progress, or fun.

Griefing can also be harassment as it is defined in the Blizzard's Harassment Policy,[1] which can result in disciplinary action for a player.

The fact that a player does not follow WoW etiquette or breaking laws in the real world (such as spreading personal information which should be taken up with proper authorities, not Blizzard) does not necessarily mean that he or she griefs other players. Griefing is generally always relative and is subject to someone's decision, rather than a granted thing. It is always preferable to let the person know that what they're doing is wrong before considering them potential griefers.

Griefing is not to be confused with exploiting, which is also mainly against the ToS, but in some cases thereof more than just a group of players have their gaming process stifled. Also, unlike griefing, exploiting is the only thing that can be addressed by the GMs.